Composition of matter and process of making it.



UNITED STATES Patented February 14, 1995.

PATENT OFFICE.

BENJAMIN FULTON GARDNER, OF CHICAGO, ILLINOIS, ASSIGNOR OF ONE-HALF TO CHARLES K. WOOLNER AND SIGMUND WOOLNER,

OF CHICAGO, ILLINOIS.

COMPOSITION OF MATTER AND PROCESS OF MAKING IT.

SPECIFICATION forming part of Letters Patent No. 782,232, dated February 14, 1905.

Application filed May 9, 1904. Serial No. 207,111.

To all whom it may concern.-

Be it known that I, BENJAMIN FULTON GARD- NER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Composition of Matter and Processes of Making It, of which the following is a specification.

This invention relates to a composition of matter which is capable of extensive use for a great variety of purposes in many different arts and alsoto the process of making it.

The object of this invention is primarily to provide an electric-resistance material for use in heaters, rheostats, controllers, switchboards, &sc.; but the composition is capable of many other uses.

In preparing the composition I use graphite, carborundum and sulfur of commerce, and commercially-pure rubber, and I have found that the composition can be successfully made with the proportions of fifty per cent. graphite, twenty-five per cent. carborundum, twenty per cent. rubber, and five per cent. sulfur,

but I do not confine myself to these proportions, as they can be varied in many respects to change the character of the composition and reduce or increase its electric resistance. I first thoroughly ,mix the carborundum, graphite, and sulfur in a dry state. I then pass the rubber through heated rolls which method to make it hard.

' tract or shrink and. will not split.

the rolls, it is soft and flexible and can be calendered to any degree of thickness or molded into any form and vulcanized by the usual I subject the composition to a carbonizing process of any suitable character after it is vulcanized. One

process of carbonization is to bury'the vulcanized composition or article made of the composition in sand and apply heat until all the sulfur .is driven off and the rubber is carbonized.

The material if made in sheets or blocks or plates can be easily worked at any stage in its .manufacture; but it will probably be found more convenient to mold thematerial mixed with the other ingredients instead of pursuing the process heretofore.described.

The degree of resistance can he graduated by.

varying the proportions of carborundum.

In its vulcanized state the material can be made flexible to a degree for certain pur-' poses and also electroplated. It can be made as soft as vulcanized rubber or as hard as glass. It is aboutas light in weight as wood.

In its finished state it does not expand or con- The material will resist the action of acids and alkali and water at any temperature.

Without limiting myself to the exact proportions or to the process of manufacture here-' in described, what I claim, and desire to secure in combining graphite, carborundurn, sulfur by Letters Patent, is and india-rubber or gutta-percha; and then 10 l. The herein described composition of matvulcanizing and carbonizing the mixture.

ter consisting of a vulcanized and carbonized 5 mixture of graphite, carborundum, sulfur and BENJAMIN FULTON GARDNER india-rubber or gutta-percha. Witnesses: 2. The herein-described process of making WM. 0. BELT,

an electric-resistance material which consists FRANCES B. ALLEN. 

